<%--验证码工具，只要在网页中输入这段代码即可：
	<iframe style="" id="validate"  marginWidth=0 frameborder="0" scrolling="no" src="< %=path % >/jsp/img.jsp" //width="60" height="18"></iframe>*/
--%>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page contentType="image/jpeg"
	import="java.awt.*,java.awt.image.*,javax.imageio.*"%>
<%!Color getRandColor(int fc, int bc) {//给定范围获得随机颜色   
		Random random = new Random();
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}%>
<%
	//设置页面不缓存   
	response.setHeader("Pragma", "No-cache");
	response.setHeader("Cache-Control", "no-cache");
	response.setDateHeader("Expires", 0);

	//   在内存中创建图象   
	int width = 60, height = 20;
	BufferedImage image = new BufferedImage(width, height,
			BufferedImage.TYPE_INT_RGB);

	//   获取图形上下文   
	Graphics g = image.getGraphics();

	//生成随机类   
	Random random = new Random();

	//   设定背景色   
	g.setColor(getRandColor(200, 250));
	g.fillRect(0, 0, width, height);

	//设定字体   
	g.setFont(new Font("Times   New   Roman", Font.PLAIN, 18));

	//画边框   
	//g.setColor(new   Color());   
	//g.drawRect(0,0,width-1,height-1);   

	//   随机产生155条干扰线，使图象中的认证码不易被其它程序探测到   
	g.setColor(getRandColor(160, 200));
	for (int i = 0; i < 155; i++) {
		int x = random.nextInt(width);
		int y = random.nextInt(height);
		int xl = random.nextInt(12);
		int yl = random.nextInt(12);
		g.drawLine(x, y, x + xl, y + yl);
	}

	//   取随机产生的认证码(4位数字)   
	String sRand = "";
	for (int i = 0; i < 4; i++) {
		//String rand = String.valueOf(random.nextInt(10));
		String rand = getRandomValue(random);
		sRand += rand;
		//   将认证码显示到图象中   
		g.setColor(new Color(20 + random.nextInt(110), 20 + random
				.nextInt(110), 20 + random.nextInt(110)));
		//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成   
		g.drawString(rand, 13 * i + 6, 16);
	}

	//   将认证码存入SESSION  key=validateCode
	session.setAttribute("validateCode", sRand);

	//   图象生效   
	g.dispose();

	//   输出图象到页面   
	ImageIO.write(image, "JPEG", response.getOutputStream());
	out.clear();
	out = pageContext.pushBody();
%>
<%!//取得随机字符
	String getRandomValue(Random random) {
		String mask = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";
		String[] masks = mask.split(",");
		return masks[random.nextInt(masks.length)];
	}%>